Chemisorption of CO and NO on molybdenum carbide foils

Wang, J.; Castonguay, Martin; McBreen, Peter H.; Ramanathan, Sasangan; Oyama, S. Ted

doi:10.1007/978-94-009-1565-7_23

Cited by 12 publications

(14 citation statements)

References 39 publications

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“…The position and the stability of the bands due to CO adsorbed on Mo 2 C/SiO 2 resemble well to that of terminally bonded CO on ␤-Mo 2 C foil [22]. We agree with the statement [22] that the characteristics of CO adsorbed on Mo 2 C are very close to that of terminally bound CO on group VIII metals.…”

Section: Co Adsorptionsupporting

confidence: 80%

“…We agree with the statement [22] that the characteristics of CO adsorbed on Mo 2 C are very close to that of terminally bound CO on group VIII metals. From the comparison of the data for Mo 2 C/Al 2 O 3 [24] and for Mo 2 C/SiO 2 presented here it can be inferred that more "metallic-like" Mo 2 C is produced on SiO 2 , than on Al 2 O 3 .…”

Section: Co Adsorptionsupporting

confidence: 80%

“…The bands at 2015 and 1850 cm −1 were assigned to terminally and bridge bonded CO species, respectively, while a very weak band at 1150 cm −1 was assigned to a "side-on" CO species. Wang et al [22] using RAIRS detected one band due to CO adsorbed on a ␤-Mo 2 C foil at 104 K. The position of this band found to be coverage dependent and shifted from 2054 cm −1 at low CO coverage to 2069 cm −1 at saturation coverage. The authors assigned this ν CO band to a terminally bound CO species and noted that its stretching frequency is characteristic of terminally bound CO on group VIII metals.…”

Section: Co Adsorptionmentioning

confidence: 99%

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Infrared study of the adsorption of CO and CH3 on silica-supported MoO3 and Mo2C catalysts

Raskó¹

2003

Applied Catalysis A: General

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Section: Co Adsorptionsupporting

confidence: 80%

Section: Co Adsorptionsupporting

confidence: 80%

Section: Co Adsorptionmentioning

confidence: 99%

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Infrared study of the adsorption of CO and CH3 on silica-supported MoO3 and Mo2C catalysts

Raskó¹

2003

Applied Catalysis A: General

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“…Adsorbed CO on a clean β-Mo 2 C foil gave rise to a ν CO band at 2069 cm -1 , and this band was assigned to adsorbed CO on Mo 2+ . A shoulder band at ∼2125 cm -1 was observed when CO was introduced to the molybdenum carbide foil which was exposed to O 2 prior to CO . This shoulder is presumably associated with CO adsorbed on an oxided Mo site.…”

Section: Discussionmentioning

confidence: 99%

Surface Sites of Alumina-Supported Molybdenum Nitride Characterized by FTIR, TPD-MS, and Volumetric Chemisorption

Yang

et al. 1998

J. Phys. Chem. B

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The surface state and active sites of a fresh Mo2N/Al2O3 were investigated by FTIR, volumetric chemisorption, and TPD-MS techniques. It has been found that adsorption properties of CO on the fresh sample are quite different from those of the reduced passivated one. For reduced passivated Mo2N/Al2O3, the IR spectrum of adsorbed CO shows that a band at ∼2180 cm-1 together with two weak bands at 2100 and 2035 cm-1 appear, suggesting that the Mo4+ cation is predominant on the surface; namely, the surface is in oxynitride form. However, for the fresh sample, adsorbed CO gives two characteristic IR bands at 2045 and 2200 cm-1, respectively, corresponding to the adsorbed CO on the molybdenum and the nitrogen sites, forming linearly adsorbed CO and NCO species. From the band position of adsorbed CO, the surface molybdenum atoms are slightly positively charged, i.e., in a state of Moδ+(0 < δ < 2). The assignment of the band at 2200 cm-1 to NCO species (CO adsorbed on N site) was further confirmed by TPD-MS and volumetric chemisorption. TPD-MS shows two CO desorption peaks at 373 and ca. 473 K, indicating two different CO adsorption sites on the catalyst. The volumetric chemisorption proves that the CO uptake increases significantly when the passivated sample is nitrided at 723 K and above, compared with the case of the reduced sample. These results suggest that not only Mo sites in low valences are present on the surface of fresh Mo nitride, but also nitrogen sites are present and so active that can react with CO to form surface NCO species.

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“…While significant effort has been applied to understanding the physical properties of metal carbides, comparatively little attention has been paid to understanding the surface chemical properties of these materials. Chemical reactions at metal carbide surfaces or interfaces are inherently related to a number of important phenomena: the oxidative stability of these materials used in high-temperature applications, the interfacial reactivity of carbide surfaces in tribological applications with lubricant species, and the chemical activity of metal carbides as catalytic materials. − Recently we have initiated an investigation of the chemical reactivity of two carbide surfaces, titanium carbide (TiC) and vanadium carbide (VC), with respect to their use as hard coatings in tribological applications. We have reported on the reactivity of molecular oxygen with the (100) face of VC and TiC and the adsorption and reaction of water on the (100) face of TiC .…”

Section: Introductionmentioning

confidence: 99%

Substrate-Dependent Reactivity of Water on Metal Carbide Surfaces

Didziulis¹,

Frantz²,

Perry³

et al. 1999

J. Phys. Chem. B

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The interaction of water with two transition metal carbides, titanium carbide (TiC) and vanadium carbide (VC), has been investigated. The adsorption, reaction, and desorption of water on the (100) face of singlecrystal samples of these materials have been studied as a function of substrate temperature over the range 100-600 K. The adsorption state of water on these surfaces has been probed with high resolution electron energy loss spectroscopy (HREELS). The reactivity of water has been directly measured with HREELS and X-ray photoelectron spectroscopy (XPS). The desorption of molecular water and the products of surface reactions has been followed with temperature programmed desorption. Collectively, these measurements indicate that water adsorbs both molecularly and dissociatively on TiC and VC; however, a greater degree of reactivity at cryogenic temperatures is observed on TiC. Dissociation of water produces surface bound hydrogen and hydroxyl groups on both surfaces and a fully dissociated surface oxide on TiC. Furthermore, a greater participation of the surface carbon atoms is observed at the TiC surface through the evolution of CO x species at elevated temperatures. The differences in surface bonding and desorption profiles are discussed in terms of differences in electronic structure of the two metal carbides. Some possible implications of these studies for the use of TiC and VC as tribological materials are also discussed.

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Chemisorption of CO and NO on molybdenum carbide foils

Cited by 12 publications

References 39 publications

Infrared study of the adsorption of CO and CH3 on silica-supported MoO3 and Mo2C catalysts

Infrared study of the adsorption of CO and CH3 on silica-supported MoO3 and Mo2C catalysts

Surface Sites of Alumina-Supported Molybdenum Nitride Characterized by FTIR, TPD-MS, and Volumetric Chemisorption

Substrate-Dependent Reactivity of Water on Metal Carbide Surfaces

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